Recent studies from this laboratory have provided some evidence that major depression,
in particular melancholia, may be accompanied by an immune response. The present study
was designed to investigate whether severe depression is characterized by increased
interleukin-6 (Il-6) activity and whether Il-6 production is related to altered levels
of acute phase reactants and to abnormal function of the hypothalamic-pituitary-adrenal
(HPA) axis. Measurements were made in 8 healthy control subjects and 24 depressed
inpatients of Il-6 production in culture supernatants of mitogen-stimulated peripheral
leukocytes and plasma levels of haptoglobin (Hp), transferrin (Tf), and postdexamethasone
cortisol. Il-6 activity was significantly higher in melancholic subjects than in healthy
control subjects and in patients with minor depression or nonmelancholic major depression.
Il-6 production was significantly correlated with Hp (positively) and Tf (negatively)
plasma levels. There were significant and positive correlations between Il-6 activity
and postdexamethasone cortisol values. The findings may suggest that increased Il-6
activity in severe depression is related to hypotransferrinemia, hyperhaptoglobinemia,
and hyperactivity of the HPA axis.